Institute of Biochemical Physics, Russian Academy of Sciences, 119334 Moscow, Russian Federation.
Rapid Commun Mass Spectrom. 2011 Jan 15;25(1):184-90. doi: 10.1002/rcm.4855.
Oxidative and nitrosative stress leaves footprints in the plant chloroplast in the form of oxidatively modified proteins. Using a mass spectrometric approach, we identified 126 tyrosine and 12 tryptophan nitration sites in 164 nitrated proteolytic peptides, mainly from photosystem I (PSI), photosystem II (PSII), cytochrome b(6) /f and ATP-synthase complexes and 140 oxidation products of tyrosine, tryptophan, proline, phenylalanine and histidine residues. While a high number of nitration sites were found in proteins from four photosynthetic complexes indicating that the nitration belongs to one of the prominent posttranslational protein modifications in photosynthetic apparatus, amino acid oxidation products were determined mostly in PSII and to a lower extent in PSI. Exposure of plants to light stress resulted in an increased level of tyrosine and tryptophan nitration and tryptophan oxidation in proteins of PSII reaction center and the oxygen-evolving complex, as compared to low light conditions. In contrast, the level of nitration and oxidation of these amino acid residues strongly decreased for all light-harvesting proteins of PSII under the same conditions. Based on these data, we propose that oxidative modifications of proteins by reactive oxygen and nitrogen species might represent an important regulatory mechanism of protein turnover under light stress conditions, especially for PSII and its antenna proteins.
氧化应激和硝化应激会在植物叶绿体中留下氧化修饰蛋白的痕迹。我们采用质谱分析法，在 164 个硝化肽中鉴定出 126 个酪氨酸和 12 个色氨酸硝化位点，这些硝化肽主要来自光系统 I（PSI）、光系统 II（PSII）、细胞色素 b6/f 和 ATP 合酶复合物，以及 140 个酪氨酸、色氨酸、脯氨酸、苯丙氨酸和组氨酸残基的氧化产物。虽然在四个光合作用复合物的蛋白质中发现了大量的硝化位点，表明硝化属于光合作用装置中一种突出的翻译后蛋白质修饰，但氨基酸氧化产物主要在 PSII 中确定，在 PSI 中则较低。与低光照条件相比，植物暴露在光胁迫下会导致 PSII 反应中心和放氧复合蛋白质中天冬氨酸和色氨酸的硝化和氧化水平增加。相比之下，在相同条件下，所有 PSII 的光捕获蛋白的这些氨基酸残基的硝化和氧化水平均大幅下降。基于这些数据，我们提出活性氧和氮物种对蛋白质的氧化修饰可能代表了光胁迫条件下蛋白质周转的重要调节机制，特别是对 PSII 和其天线蛋白而言。
